episode34

034 How Lateral Inhibition Enhances Visual Edges

Leslie Samuel IBTV, Physiology, Sense Organs 92 Comments

In this video, Leslie explains all about lateral inhibition using two rectangles. Watch to learn how this process helps us see edges of objects more clearly. Enjoy!

Transcript of Today’s Episode

Welcome to another episode of Interactive Biology TV, where we’re making biology fun! My name is Leslie Samuel. In this episode, Episode 34, I’m going to talk about how lateral inhibition enhances visual edges. What am I talking about? Well, you’re going to see right now.

Here, we have 2 rectangles. One is darker and the other is lighter. It’s just a solid gray color over here, and a solid darker gray, almost black color, over here. What I’m going to do is I’m going to show you something that’s quite fascinating, at least it’s fascinating to me. It illustrates how visual processing can lead to some interesting things. To a certain extent, it shows that what you see is not always what’s there.

What am I talking about? Well, what I’m going to do is I’m going to take this gray rectangle over here and I’m basically going to move it towards the other one. We’re going to see what happens. Remember it’s a solid gray color, the same color that I have over here, it’s the same color that I have over here, and throughout the entire rectangle. Now let’s put them together and see if anything happens. So I’m just going to move the one on the right towards the one at the left. And now, hopefully you can see this, depending on the monitor that you’re using, you may or may not be able to see this, but I’m guessing you will be able to see it.

What you’re going to notice here is right here at the border, you’re going to see that here is just a little lighter than over here. So before, it looked like a solid gray object, and I really hope you see this, or else this is pointless, and over here now, we’re seeing that it’s darker here than it is over here. If you don’t see it, look closely at the monitor and see if you see a little bit of a lighter edge here.

Now, is that lighter edge there? No, it really isn’t. But there’s something that’s happening inside your eye that’s making it seem as if it’s lighter over here and a little darker over here, you might be able to see that also. So, lighter on this side, and darker on this side, just a little bit. What we’re going to do is look at why that’s the case.

The main idea, though, is that the brain is set up to enhance visual edges so that you can see the edges more clearly. I find this to be very fascinating because to me, it illustrates that maybe what we see might not actually be what is there. And I don’t know how much that extends into everyday life, but it’s an interesting concept nonetheless. Now, let’s look at the cells that we have in the retina.

We looked at this already. We said that here we have the rods and this would be a cone, we said that here we have a horizontal cell, and here we have ganglion cells, and we also have amacrine cells. This is just a review of an earlier episode. The cell that I’m most concerned with now in terms of this process is the horizontal cell. You can see here, we have a number of rods, and we have a cone, and this horizontal cell goes laterally, and it connects to multiple rods and even connects to some of the cones. This is where the processing that enhances those visual edges starts.

So it’s happening in the retina, this entire thing is in the retina. What happens is if it’s getting a lot of intense stimulation from a group of rods over here, that causes this horizontal cell to inhibit some of the other cells so you do not get as much stimulation from those receptors that are not stimulated as intensely as these over here. So we have a strong stimulation coming via these rods or these receptor cells, and that’s causing inhibition of some of the cells that are not being stimulated as much. This process is called lateral inhibition, and to me it’s a very fascinating concept, showing that strong activity over here can inhibit activity in another area.

That’s all I want to cover in this episode. That’s it for this video. If you have any questions or comments, go ahead and leave them below, and I’ll be happy to take a look at them, and maybe even answer the questions that you might have. That’s all for now, and I’ll see you in the next video.

Comments 92

  1. actos386

    Hello, I want to let you know that I love your job, because it gives me a 3D vision of what I´m studyng, so don´t be surprised if you see that I like all your videos.
    What I want to ask you is about your bibliography. You see, my teacher is really strict when it comes to that point, he wants us to get the best info, and the last editions.
    Other question is: do you know any information about the bipolar receptors and the cones and rodes neurotransmitters?

  2. actos386

    Hello, I want to let you know that I love your job, because it gives me a 3D vision of what I´m studyng, so don´t be surprised if you see that I like all your videos.
    What I want to ask you is about your bibliography. You see, my teacher is really strict when it comes to that point, he wants us to get the best info, and the last editions.
    Other question is: do you know any information about the bipolar receptors and the cones and rodes neurotransmitters?

  3. actos386

    Hello, I want to let you know that I love your job, because it gives me a
    3D vision of what I´m studyng, so don´t be surprised if you see that I like
    all your videos. What I want to ask you is about your bibliography. You
    see, my teacher is really strict when it comes to that point, he wants us
    to get the best info, and the last editions. Other question is: do you know
    any information about the bipolar receptors and the cones and rodes
    neurotransmitters?

  4. actos386

    Hello again
    I forgot to tell you: keep doing this! you are helping a lot of people. This is the future of studying. Im not saying that I dont beleieve in classes, I love the. I also think books are really important, but this can really clear my mind when I see how exactly the proccess happens.
    Thanks!!!

  5. actos386

    Hello again
    I forgot to tell you: keep doing this! you are helping a lot of people. This is the future of studying. Im not saying that I dont beleieve in classes, I love the. I also think books are really important, but this can really clear my mind when I see how exactly the proccess happens.
    Thanks!!!

  6. actos386

    Hello again I forgot to tell you: keep doing this! you are helping a lot of
    people. This is the future of studying. Im not saying that I dont beleieve
    in classes, I love the. I also think books are really important, but this
    can really clear my mind when I see how exactly the proccess happens.
    Thanks!!!

  7. InteractiveBiology

    @actos386 Thank you so much for your kind words. I’m glad you’re finding value in the content of this video.

    In terms of the bibliography, yes that is very important when you are publishing stuff. You want to give credit where credit is due. I don’t post a bibliography on these videos because these are all from my notes I took when I was in college.

    Yes, I do have info on bipolar cells in the visual cortex. They are explained in episode 35 of my videos. Check it out.

  8. InteractiveBiology

    Thank you so much for your kind words. I’m glad you’re finding value in the content of this video.

    In terms of the bibliography, yes that is very important when you are publishing stuff. You want to give credit where credit is due. I don’t post a bibliography on these videos because these are all from my notes I took when I was in college.

    Yes, I do have info on bipolar cells in the visual cortex. They are explained in episode 35 of my videos. Check it out.

  9. InteractiveBiology

    @actos386 Thank you so much for your kind words. I’m glad you’re finding
    value in the content of this video. In terms of the bibliography, yes that
    is very important when you are publishing stuff. You want to give credit
    where credit is due. I don’t post a bibliography on these videos because
    these are all from my notes I took when I was in college. Yes, I do have
    info on bipolar cells in the visual cortex. They are explained in episode
    35 of my videos. Check it out.

  10. InteractiveBiology

    @actos386 Thank you again. I do agree that the internet will play a MAJOR role in how education happens. More and more people are going to have access to this type of knowledge as technology advances and people are able to access this type of info from anywhere.

    Thank you for the encouragement!

  11. InteractiveBiology

    Thank you again. I do agree that the internet will play a MAJOR role in how education happens. More and more people are going to have access to this type of knowledge as technology advances and people are able to access this type of info from anywhere.

    Thank you for the encouragement!

  12. Nikki Georgiou

    all of this is great! after hours of reading on this, i finally get it in
    just one hour of watching your video!!

  13. InteractiveBiology

    @Mansuya Wow, thanks for your comment. Those kinds of comments give me the motivation I need to continue making these videos.

    All the best!

  14. InteractiveBiology

    @Mansuya If you watch the video again, you will see an example of what I mean. When I put the two rectangles together, you should see one becoming lighter. Watch it carefully.

  15. Bas

    Hello, can i see this as a sort of cross-over distortion like in a stereo
    audio amplifier when the signal of one channel is picktup by the other?

    1. Post
      Author
  16. InteractiveBiology

    @youremocional All questions are answered in the Interactive Biology community forums from now on. Go to the website in the description and then visit the community. This is to make it as efficient as possible as we have multiple people over there to help answer questions.

    All the best

  17. InteractiveBiology

    All questions are answered in the Interactive Biology community forums from now on. Go to the website in the description and then visit the community. This is to make it as efficient as possible as we have multiple people over there to help answer questions.

    All the best

  18. zusamin1

    lighter becomes lighter. darker becomes darker. darker side gets more inhibted as it is less stimulated than the lighter side.
    But why the edge on darker side looks even darker? more inhibition reached to the edge than the far end?
    Lighter side looks lighter in the edge why? are there inhibition to the non-edge side of the lighter side? why?
    Is there selective inhibition to cons and rods?
    im so confused :s

  19. InteractiveBiology

    @zusamin1 All questions are answered in the Interactive Biology community forums from now on. Go to the website in the description and then visit the community. This is to make it as efficient as possible as we have multiple people over there to help answer questions.

    All the best

  20. zusamin1

    lighter becomes lighter. darker becomes darker. darker side gets more inhibted as it is less stimulated than the lighter side.
    But why the edge on darker side looks even darker? more inhibition reached to the edge than the far end?
    Lighter side looks lighter in the edge why? are there inhibition to the non-edge side of the lighter side? why?
    Is there selective inhibition to cons and rods?
    im so confused :s

  21. InteractiveBiology

    All questions are answered in the Interactive Biology community forums from now on. Go to the website in the description and then visit the community. This is to make it as efficient as possible as we have multiple people over there to help answer questions.

    All the best

  22. pfshepherd2010

    Is it bad if I don’t see the lighter edge when you combine the two shades of gray? I am using a 1080p, 120hz, 22inch computer monitor and full screen 720p hd video stream. I don’t see it. I have looked at other pictures and videos that demonstrate this concept and I still don’t see but my friend does. What does this mean about my eyes? Am I going color blind?

  23. pfshepherd2010

    Is it bad if I don’t see the lighter edge when you combine the two shades of gray? I am using a 1080p, 120hz, 22inch computer monitor and full screen 720p hd video stream. I don’t see it. I have looked at other pictures and videos that demonstrate this concept and I still don’t see but my friend does. What does this mean about my eyes? Am I going color blind?

  24. InteractiveBiology

    @pfshepherd2010 Unfortunately, Leslie has a lot of work to do right now to be able to attend to the number of emails he’s been receiving lately. I would strongly suggest though that you go and see an eye doctor about your observations just to be sure. We hope it’s nothing that complicated… Do take care!

  25. InteractiveBiology

    Unfortunately, Leslie has a lot of work to do right now to be able to attend to the number of emails he’s been receiving lately. I would strongly suggest though that you go and see an eye doctor about your observations just to be sure. We hope it’s nothing that complicated… Do take care!

  26. pfshepherd2010

    Is it bad if I don’t see the lighter edge when you combine the two shades of gray? I am using a 1080p, 120hz, 22inch computer monitor and full screen 720p hd video stream. I don’t see it. I have looked at other pictures and videos that demonstrate this concept and I still don’t see but my friend does. What does this mean about my eyes? Am I going color blind?

  27. InteractiveBiology

    Unfortunately, Leslie has a lot of work to do right now to be able to attend to the number of emails he’s been receiving lately. I would strongly suggest though that you go and see an eye doctor about your observations just to be sure. We hope it’s nothing that complicated… Do take care!

  28. bigdaddykenkuo

    This video is incredibly resourceful. I’m using this to study for my Behavioral Neuroscience Exam. Thank you, and I like your accent.

  29. Yvonne

    Thank you so much for posting the video’s on the Special Senses! We have a test on Tuesday and your video’s always make things clear to me.

  30. shoutatthesky

    I don’t see it either. When I first heard about lateral inhibition I was blown away. This video does not describe it well. I don’t think there is anything wrong with your eyes just this person’s description of the concept.

  31. shoutatthesky

    I don’t see it either. When I first heard about lateral inhibition I was blown away. This video does not describe it well. I don’t think there is anything wrong with your eyes just this person’s description of the concept.

  32. ilikephilipp

    Not necessarily. I couldn’t see it at all, at first. The two rectangles are diffferent colors (you do see that part, right?). One is grey (on the right), the other is dark grey (to me, it looks black). When Leslie brought the two rectangles in contact, the thing I can see clearly is that they are, in fact, different colors. One is darker, (left one), one is lighter (right one). The thin strip Leslie is talking about is very small, and’s at the very edge of the border between the two rectangles.

  33. ilikephilipp

    Not necessarily. I couldn’t see it at all, at first. The two rectangles are diffferent colors (you do see that part, right?). One is grey (on the right), the other is dark grey (to me, it looks black). When Leslie brought the two rectangles in contact, the thing I can see clearly is that they are, in fact, different colors. One is darker, (left one), one is lighter (right one). The thin strip Leslie is talking about is very small, and’s at the very edge of the border between the two rectangles.

  34. ilikephilipp

    It doesn’t even look like a lighter border — the definition is very faint, and my brain is overriding it by telling me that it is just the two rectangles. This might be the case with you, as well. The border IS very fine — more of a shimmering at the edge, than a real color difference — it’s just a minor detail, one of those blink-it-and-you’ll-miss-it, kind of things.

  35. ilikephilipp

    It doesn’t even look like a lighter border — the definition is very faint, and my brain is overriding it by telling me that it is just the two rectangles. This might be the case with you, as well. The border IS very fine — more of a shimmering at the edge, than a real color difference — it’s just a minor detail, one of those blink-it-and-you’ll-miss-it, kind of things.

  36. ilikephilipp

    Comment was too long. Read my comment entitled “Not necessarily” first, then the “It doesn’t…” one.

    Best of luck to you!

  37. Hordkorowiec328

    Could someone give a link to that community forums? I couldn’t find it on IB site :-/. And I am too a bit confused. Inhibition coming out from more stimulated cells (light color) would result in dark color being perceived as even darker near the edge. I, however, see area around the black figure as somewhat lighter so there has to be extra stimulation going on. However, I guess that the point of the video was to give a general idea how it works (Ie, that it happens in retina – not in brain)

  38. Michael McPartlin

    Videos are great. The voice is very easy to listen to and the content is correct. Unfortunately, I am unable to see the gradient in color once the black and grey box meet. I am unsure of whether or not my monitor is bad or my eyes are bad. Either way, thanks for the content.

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